how do i test antioxidant activity on an apple slice?

i only got a few information from science buddies which was this:
Antioxidants have become very popular in the news lately for their potential health and anti-aging properties. Antioxidants work by preventing oxidation reactions that produce free-radicals which can cause harm to the body. Try testing different vitamins for antioxidant activity. How do vitamins A, B, C, and E compare? Do some vitamins have more antioxidant activity than others? What are some other sources of antioxidants? Try testing extracts from proposed sources of antioxidants like coffee, tea, tomatoes, carrots, grapes, and berries (MedlinePlus, 2006). Do nuts contain antioxidants? Does roasting or processing affect the antioxidant properties of nuts? (Hopkins and Watts, 2003) A simple way to test for antioxidant activity is to see if the reagent can keep an apple slice from browning.

I still don’t get what there asking me to do though, and is this a good project to do on the human body?

Its a crude experiment but you could mix the chemical you are interested in with water and then brush it onto the surface of a cut apple. Compare the time it takes for browning to occur with a second slice which you have brushed with water but not containing any of the "antioxidant" chemical. It is difficult to do on the human body because there wouldn’t be any quickly observable effects to monitor although probably not harmful as long as you limited the experiment to food products. Application of food to the human body is not covered under this Yahoo topic section.